/Engine/Source/Editor/GraphEditor/Public/SNodePanel.h
The user is responsible for creating widgets (which must be derived from SNode) and any custom drawing code desired. The other main restriction is that each SNode instance must have a unique UObject* associated with it.
namespace ENodeZone { enum Type { TopLeft, TopCenter, TopRight, Left, Center, Right, BottomLeft, BottomCenter, BottomRight, Count, } }